Our epidemiologic research, aimed at the identification of precursory factors for high blood pressure in young persons, is based on longitudinal observations of blood pressure and of concomitant variables of mothers and their children. The bases for our research are twofold. First, we plan to use the extensive data that have been collected in a prospective, longitudinal cohort study, which started with some 20,000 pregnant women and proceeded with observations on the children born from these pregnancies. Secondly, we plan to extend our observations with a follow-up examination of a subcohort of about 2,000 mothers and their children when the latter are about 16 years old. Parallel to this examination we plan a medical record review of parents and child. A large part of the data has already been assembled and is maintained as a research tool by the Child Health and Development Studies (CHDS). The basic study cohort of CHDS consists of some 20,000 pregnant women and the children born from these pregnancies. The families resided in the San Francisco Bay Area and were members of a prepaid medical plan, Kaiser Foundation Health Plan, which provides comprehensive medical care for the entire family. The Child Health and Development Studies were designed and initiated in 1959 by Dr. J. Yerushalmy, and are a research unit of the School of Public Health, University of California at Berkeley.